Chapman-Enskog asymptotic procedure in structured population dynamics

Complexity of many biological models often makes impossible their robust theoretical and numerical analysis and thus requires a systematical method of reducing the number of variables in the system in such a way that the dynamics of the simplified model approximates the original way in a reasonable way. Such an aggregation of variables is often done by ad hoc methods. In turns out that in many biological systems the well-known Chapman-Enskog asymptotic procedure is well suited for aggregation which then can be viewed as passing from a microscopic (kinetic) to a macroscopic (hydrodynamic) description of the system. We demonstrate this approach by applying it to an age- and space-structured population model

Diagnostics of the Generation, Decay, and Transport of Artificial Plasma Perturbations by Means of Short Pulses of High-Power Radio Waves

© 2017 Springer Science+Business Media New YorkWe discuss the techniques of measuring and the possibilities of using short pulses of high-power radio waves for diagnostics of the properties of high- and low-frequency ionospheric plasma turbulence. The results of the experimental studies performed using the Sura heating facility are presented

The measurement of the ionospheric total content variations caused by a powerful radio emission of "sura" facility on a network of GNSS-receivers

© 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.Observations of the perturbations of total electron content (TEC) caused by a powerful radio emission of "Sura" facility (Radio Physical Research Institute, N. Novgorod) were carried out during several experimental campaigns from March of 2010 to March 2013. In this paper the data of experimental measurements of TEC-variations conducted on March, 15, 2010 and on March, 12, 2013, are presented. Parameters of TEC-variations were obtained by dual-frequency global navigation satellite systems (GNSS) diagnostics. Registration of signal parameters from GNSS-transmitters was performed at spatially separated sites along the geomagnetic latitude: Vasilsursk (56°08′N, 46°05′ E), Zelenodolsk (55°52′N, 48°33′E) and Kazan (55°48′N, 49°08′E). In the experiments radio path from GNSS satellite to Vasilsursk passed over the disturbed region of ionosphere, but radio paths to Zelenodolsk and to Kazan did not. However, TEC-variations correlated with pumping of ionosphere by "Sura" facility were detected for all up to three ground measurements sites. Magnitudes of TEC-variations reached up to ∼0.6-0.7 TECU. The speculation that a sharp gradient of the electron density formed at the border of the main lobe of "Sura" facility may cause the generation of IGW is presented

Dynamics of large-scale ionospheric inhomogeneities caused by a powerful radio emission of the Sura facility from the data collected onto ground-based GNSS network

© 2017, Pleiades Publishing, Ltd.The measurements of variations in the total electron content of the Earth’s ionosphere along the GPS satellite signal propagation path are described. The signal parameters were measured at a network of receivers at three distant sites: Sura (Vasilsursk), Zelenodolsk, and Kazan. They are arranged along the geomagnetic latitude of the Sura Facility under short-wave radio irradiation of the ionosphere. One feature of the experiment is the crossing of a disturbed region by the radio path between a GPS satellite and Vasilsursk. This resulted from the angular sizes of the Sura array pattern; the radio paths between a GPS satellite and Zelenodolsk and a GPS satellite and Kazan did not cross. Variations in the total electron content of up to 0.15−0.3 TECU were revealed at all three sites during four experimental campaigns (March 2010, March 2013, May 2013, and November 2013). The lateral scale of an ionospheric disturbance stimulated by a high-power radio wave and the velocity of its west-to-east propagation along the geomagnetic latitude were 30–60 km and 270–350 m/s, respectively. A decrease in the total electron content (down to 0.55 TECU) was recorded along the Kazan–Zelenodolsk–Vasilsurks line, which is connected with the solar terminator transit; the lateral scale of the related ionospheric inhomogeneities was ~65–80 km

Mutual Allocation of the Artificial Airglow Patches and Large-Scale Irregularities in the HF-Pumped Ionosphere

©2018. American Geophysical Union. All Rights Reserved. The paper reports first simultaneous observations of artificial emission of 630-nm oxygen red line, along with perturbations of slant total electron content (STEC). They were induced by the high-frequency (HF) ionospheric heating produced by the SURA facility situated near Nijniy Novgorod, Russia. The HF heating affects differently the optical emission and STEC. While the patches of the artificial airglow are close to the area of the reduced STEC, the STEC increases at the periphery of the patches. Thus, the artificial airglow occurs mostly inside the large plasma cavities

Determining the Position and Properties of the Region of Artificial Ionospheric Irregularities Above the Sura Facility Responsible for Generation of Aspect Scattering Signals on a Short Path

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. The data obtained in the experiments on aspect scattering on a short path of Kazan—Vasilsursk—Kazan performed at the Sura facility in 2010 at frequencies of 2–7 MHz are compared with the results of ray-tracing calculations of the sounding and scattered signals. Positions and sizes of the region above Sura responsible for generation of the aspect scattering signals are determined. Characteristic scales of artificial decameter scattering irregularities and their dynamic properties as functions of the generation altitude and the time of the day are found

Airglow during ionospheric modifications by the sura facility radiation. Experimental results obtained in 2010

We present the results of studying the structure and dynamics of the HF-heated volume above the Sura facility obtained in 2010 by measurements of ionospheric airglow in the red (λ = 630 nm) and green (λ = 557.7 nm) lines of atomic oxygen. Vertical sounding of the ionosphere (followed by modeling of the pump-wave propagation) and measurements of stimulated electromagnetic emission were used for additional diagnostics of ionospheric parameters and the processes occurring in the heated volume. © 2012 Springer Science+Business Media, Inc

The 630 nm and 557.7 nm Airglow During HF Ionosphere Pumping by the SURA Facility Radiation for Pump Frequencies Near the Fourth Electron Gyroharmonic

© 2015, Springer Science+Business Media New York. We present the results of analysis of the dependence of the ionospheric airglow in the red (630 nm) and green (557.7 nm) lines of atomic oxygen on the pump-wave frequency f0 near the fourth electron gyroharmonic 4fce. The experimental data were obtained in 2012 using the SURA heating facility. Stimulated electromagnetic emission spectra were used to determine the relation between f0 and 4fce. It is found that at f0 > 4fce and δf = f0 − 4fce ≈ 15–20 kHz the red-line airglow intensity is about a factor of 1.5 higher for the magnetic zenith pumping (when the pump beam is inclined 12° south of the magnetic field direction) than for the vertical pumping. In the green line for the same offsets δf, the airglow was recorded with confidence only during magnetic zenith pumping. During vertical pumping, no regular dependence of the red-line airglow intensity on δf in the range −15 < δf < 280 kHz was obtained, while the green-line airglow was observed at 15 < δf < +5 kHz and 230 < δf < 280 kHz. In the red line during vertical pumping, a change from the artificial airglow generation to the ionospheric background suppression was detected when the F-layer cutoff frequency was decreased. During magnetic zenith pumping, a wide (about 30°) background suppression zone was observed around the airglow spot with an about 6° angular width